The present invention relates to display controllers for electro-optic image displays, and particularly to such controllers having power saving features.
The electronic drive circuits that control electro-optic image displays in digital image display systems, such as liquid crystal displays (“LCDs”), consume significant power to maintain and continuously update the display. These circuits, known as display controllers, typically send both digitized image data and control signals to the electro-optic image display. Such displays commonly operate in one of two modes: full display, in which an image is displayed and updated, and display blank, in which a blank black or white screen is displayed. In full display mode all the data signals and control signals to the LCD toggle, which produces maximum power consumption by the display controller. In display blank mode only the control signals to the LCD are toggled, resulting in a black or white image on the display and minimum power consumption by the display controller.
There are situations where power savings in digital image display systems is particularly desirable. That is the case, for example, in portable computers that operate off battery power. While image blank mode can be used to save power when there is no need to see an image, often there is a need, or at least an advantage, to be able to observe an image even if the image is not the center of activity or attention. Accordingly, it would be useful to be able to reduce display controller power consumption without eliminating the image.